Naslov
Smectitization as a Trigger of Bacterially Mediated Mn-Fe Micronodule Generation in Felsic Glass (Livno-Tomislavgrad Paleolake, Bosnia and Herzegovina)

Autori
Badurina, Luka ; Šegvić, Branimir ; Mandic, Oleg ; Zanoni, Giovanni

Izvornik
Minerals (2075-163X) 10 (2020), 10; 899-911

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, ostalo

Ključne riječi
felsic glass alteration ; smectitization ; Mn-Fe micronodules ; biomineralization

Sažetak
Miocene tuffs preserved in argillaceous sediment interbedded with lacustrine successions are commonly encountered throughout the Dinarides Lake System (DLS) in south- eastern Europe. In this contribution the volcanic glass degradation and co-genetic Mn-Fe precipitation were studied in a 14.68 Ma felsic tuff from DLS Livno-Tomislavgrad Basin. Microbial activity has been involved in both reactions thus adding the interest of revealing effects of biotic and abiotic processes taking place during tuff eogenesis. X-ray diffraction and electron microbeam analysis with energy- dispersive X-ray spectroscopy revealed the pitting or granular structures developed at glass rims along with smectite flakes protruding from a degrading glass. Mn-Fe mineralization emerges in the form of Mn-Fe coatings, an initial step to micronodule formation, where traces of biogenetic influence included a high content of phases rich in structural Mn (IV) (i.e., ranciéite and jacobsite) and presence of microbial microfossils. Co-genetic ties between glass degradation and Mn-Fe precipitation were established through the report of dioctahedral smectite formed out of altered glass ; which then served as nuclei of the ongoing biotic and abiotic Mn-Fe mineralization. These processes manifest on a continuous involvement of microbial life in the course of eogenesis of pyroclastic material in lacustrine environments.

Izvorni jezik
Engleski

Znanstvena područja
Geologija

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